Claudin-low Triple-negative Breast Cancer Research Articles

Microelectrode bioimpedance analysis distinguishes basal and claudin-low subtypes of triple negative breast cancer cells.

Triple negative breast cancer (TNBC) is highly aggressive and has a poor prognosis when compared to other molecular subtypes. In particular, the claudin-low subtype of TNBC exhibits tumor-initiating/cancer stem cell like properties. Here, we seek to find new biomarkers to discriminate different forms of TNBC by characterizing their bioimpedance. A customized bioimpedance sensor with four identical branched microelectrodes with branch widths adjusted to accommodate spreading of individual cells was fabricated on silicon and pyrex/glass substrates. Cell analyses were performed on the silicon devices which showed somewhat improved inter-electrode and intra-device reliability. We performed detailed analysis of the bioimpedance spectra of four TNBC cell lines, comparing the peak magnitude, peak frequency and peak phase angle between claudin-low TNBC subtype represented by MDA-MB-231 and Hs578T with that of two basal cells types, the TNBC MDA-MB-468, and an immortalized non-malignant basal breast cell line, MCF-10A. The claudin-low TNBC cell lines showed significantly higher peak frequencies and peak phase angles than the properties might be useful in distinguishing the clinically significant claudin-low subtype of TNBC.

Abstract A27: Dissecting the functional landscape of triple-negative breast cancer

Abstract Our group employed a pangenomic loss of function screening approach to systematically dissect the molecular architecture that functionally supports Triple Negative Breast Cancer (TNBC). Given that treatment options for this disease are typically limited to cytotoxic therapies, we applied a paclitaxel-based synthetic lethal approach to identify those molecular components that modulate chemoresponsiveness. To account for heterogeneity within the patient population, we screened 4 triple negative tumor-derived breast cancer cell lines that represent the spectrum of TNBC oncogenic aberrations and chemoresponse profiles. We also accounted for the two molecular subtypes, Claudin-Low and Basal-Like, that comprise the majority of TNBC cases. These screens revealed a number of core modulators of tumor cell viability and paclitaxel-induced cellular stress that have not been previously appreciated for supporting TNBC biology at the cell autonomous level. For example, this strategy implicated AMPK family member, SIK2, as a key nutrient sensor that may inhibit excessive autophagy. Inhibition of SIK2 leads to enhanced autophagic flux and a loss of cell viability in a variety of TNBC genetic backgrounds. In addition, we discovered the signaling supported by the cytokine receptor, CXCR3, and its ligand, CXCL9, to be repurposed to promote mitotic fidelity and thus, tumor cell fitness specifically in the Basal-Like TNBC molecular subtype. Finally, we uncovered a requirement for the transcription factor, ZNF165, in specifying the gene expression profiles activated by TGFβ signaling. In particular, the TGFβ target protein, SERPINE1, is required to promote prosurvival signaling in the Claudin-Low TNBC molecular subtype. Given that the expression of ZNF165 is otherwise restricted to the male testes, ZNF165 may represent a mechanism by which tumors engage anomaly-expressed proteins to promote survival. Taken together, we have uncovered novel tumor cell vulnerabilities in TNBC that could be therapeutically leveraged to enhance current therapeutic approaches. Citation Format: Kimberly Maxfield, Aleix Prat, Kathleen Corcoran, Angelique Whitehurst. Dissecting the functional landscape of triple-negative breast cancer. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr A27.

Improving mouse models

Knight et al. have developed a mouse model that resembles the claudin-low subtype of triple-negative breast cancer (TNBC) by expressing a weakly oncogenic MET receptor tyrosine kinase under the control of the mouse mammary tumour virus promoter concomitant with conditionally deleting Trp53 in the mammary gland. Tumours in these mice have a similar molecular signature to human claudin-low TNBC, and require MET for proliferation and for maintaining the claudin-low morphological phenotype. Therefore, MET inhibitors may be effective against TNBC.

Abstract P6-11-13: In vitro antineoplastic evaluation of rationally designed naphtoquinone-derived drugs in triple-negative breast cancer cell line

Abstract Background: Breast cancer (BC) comprises multiple diseases harboring different genetic alterations, which subtypes respond differently to treatment, and are associated to distinct clinical outcomes. Likewise, triple negative breast cancer (TNBCs) are a heterogeneous subgroup of BC, immunophenotypically negative for estrogen and progesterone receptor, and HER2, that account for 10–15% of all invasive BC, affecting mostly African-American and Hispanic pre-menopausal women. Considering that TNBC have poor prognosis, and cannot be effectively treated with current targeted therapies, the discovery of new treatment options is imperative. Methods: Novel naphtoquinone-derived drugs were rationally designed to act through multiple pathways aiming the avoidance of drug-resistant phenotype acquisition by tumor cells, and were synthesized following high efficiency and low cost method. Drugs antineoplastic efficacy (AE) was accessed in claudin-low TNBC cell line, MDA-MB-231, through the evaluation of cellular metabolic viability (CMV) (MTT method). Drugs structures are protected by patent. Cells were cultured in RPMI media supplemented with 10% (v/v) FBS and antibiotics until subconfluence; then, 1.5×105 cells/well were subcultured for 72h prior to treatment with drugs (10−4, 10−5, 10−6, 10−7, and 10−8 M). After 24h, CMV was assessed. Experiments in which the lineage was treated with cisplatin, doxorubicin or paclitaxel were run in parallel. The mean and standard-deviation of the absorbancies were used to calculate CMV and drugs IC50 (PrismaGraphPad version 5.1). Findings: We screened the AE of 43 novel naftoquinones-derived drugs in MDA-MB-231 lineage; seven have decreased its CMV by, at least, 50%, as: PIC1 (IC50 1.15×10−4M; CMV decrease of 50%); PIC6 (IC50 4.24×10−5M; CMV decrease of 70%); PIC10 (IC50 5.07×10−5M; CMV decrease of 70%); PIC 20 (IC50 1.38×10−5M; CMV decrease of 90%); PIC21 (IC50 5.00×10−5M; CMV decrease of 70%); S5 (IC50 7.26×10−5M; CMV decrease of 60%); M20 (IC50 7.94×10−5M; CMV decrease of 60%). Their AE was significantly higher than that of cisplatin (IC50 1.56×10−4M; CMV decrease < 10%), doxorubicin (IC50 1.76×10−4M; CMV decrease of 38%), and paclitaxel (IC50 5.05×10−7M; CMV decrease of 20%). Interpretation: Altogether, our results present potential novel antineoplastic drugs to treat TNBC from a panel of in house rationally designed naftoquinones-derived compounds, developing an innovative and economically viable project. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-13.